Density functional theory modeling of C-Au chemical bond formation in gold implanted polyethylene

We have studied processes of gold ion implantation in polyethylene (PE) by theoretical chemistry methods. Car-Parrinello molecular dynamics (CPMD) simulations of collisions and following chemical kinetics considerations lead to the conclusion that chemical bonds between gold atoms and PE chains are formed. We have identified and characterized by a DFT method various stable structures with C-Au, C-Au-C, C-Au-H and C-AuH₂ types of chemical bonds. The binding energies (BE) of C-Au bonds are as high as 227 kJ mol^-1 and the bond analysis reveals a covalent bonding character. For the experimental detection of these structures in gold implanted PE, we predicted characteristic infra-red (IR) frequencies. The C-Au stretching vibrational modes lie around 500 cm^-1. Other characteristic frequencies lie in a band between 730 cm^-1 and 1500 cm^-1.